1. Field of Invention
The present invention relates to a method and apparatus for writing a code on an optical element; and more particularly, for a method and apparatus for writing a 2-dimensional code on a very small optical element in the form of a microbead that may be 1-1000 microns or smaller.
2. Description of Related Art
Tiny microbeads that are individually identifiable have many applications in drug discovery, genomics, chemistry, and security. Microbeads are very small objects, typically 1-1000 microns (um) in feature size. They may be cylindrical, cubic, rectangular, or any other shape. Coded microbeads are individually identifiable. There are many methods available to encode microbeads. Known methods for encoding microbeads include fluorescence intensity and/or color, chemical techniques, spatial marks on the particles and radio-frequency encoding. However, the known ways involve writing a code that is linear which limits the amount of information that can be contained in such a code, which in turn limits the type of applications in which the coded optical elements may be used. In view of this, there is a need in the industry for a better way to encode microbeads to increase the amount of information each microbead contains.